Automatic drain valves for air reservoirs



Jan. 17, 1967 W. M. PAGE AUTOMATIC DRAIN VALVES FOR AIR RESERVOIRS Filed Feb. 6, 1964 .I/" Jv I! ll IN EA 70R United States Patent Oflice 3,298,387 Patented Jan. 17, 1967 3,298,387 AUTOMATIC DRAIN VALVES FOR AIR RESERVOIRS Wilbur M. Page, Lincoln, England, assignor to Clayton Dewandre Company Limited, Lincoln, England, a company of-Great Britain Filed Feb. 6, 1964, Ser. No. 342,978 Claims priority, application Great Britain, Feb. 11, 1963, 5,451/63 7 Claims. (Cl. 137-203) This invention relates to automatic drain valves for the air reservoirs used in air-pressure braking apparatus and similar compressed air systems and particularly to drain valves of the type in which reservoir pressure is used to discharge condensation draining into the valve. The present invention provides a new or improved drain valve of this character which is reliable under all conditions of use and which cannot operate in such manner as to vent the reservoir to atmosphere. The invention also provides an improved drain valve which has a discharge chamber of large capacity relative to the overall size of the valve and in which sliding surfaces are isolated from the fluid being drained to avoid freezing troubles and damage due to abrasive particles in the fluid.

According to the invention the improved drain valve comprises a drainage chamber or space adapted in use to communicate permanently with the reservoir, a discharge chamber having a valve-controlled inlet port, leading into the drainage chamber, and a valve-controlled outlet or atmospheric port, reciprocable valve-actuating means operable to open the inlet and outlet valves selectively, and diaphragm or equivalent pressure responsive means adapted to be subjected to a source of intermittent or fluctuating pressure and to operate said valve-actuating means, a degree of free play or lost motion being provided between the valve-actuating means and said valves such that the two valves cannot be held open simultaneously.

Reference will now be made to the accompanying drawing which is an axial section through a preferred embodiment of the invention.

The valve shown is adapted for attachment to the underside of a reservoir for which purpose the valve housing 1 is fitted at its upper side with a spigot member 2 screw-threaded for engagement with a boss 3a on the reservoir wall 3. In its upper end the housing defines a central drainage chamber 4, a vertical inlet passage 5 extending through the spigot member normally connecting this chamber to the interior of the reservoir through a filter 6 such that condensation forming in the reservoir drains into the chamber. Formed within the housing and below the drainage chamber 4 is a larger chamber 7, hereinafter termed the discharge chamber, an inlet port 8 in the wall separating the two chambers being controlled by a poppet-type valve 9, the stem 9a of which extends downwardly into the discharge chamber 7. The valve 9 is spring-loaded in the direction to close off the port 8. Formed in the lower wall of the housing is an outlet port 10 connecting chamber 7 to atmosphere, preferably through a perforated dust cap 11, this port being closable in similar manner by a spring-loaded poppet valve 12 the stem 12a of which extends upwardly into the discharge chamber 7 in axial alignment with the inlet valve steam 9a.

Extending across the discharge chamber is a transverse wall 13 and supported for vertical reciprocable movement in a bore in a central enlargement 13a of said wall is a tubular valve-actuating member indicated generally at 14, said member being attached at its upper end to the inner edge of a diaphragm 15 secured at its periphery to the housing, and at its lower end to a diaphragm to similarly mounted. Conveniently, the housing is formed of three sections secured together by bolts 17, the pcripheral portions of the diaphragms being clamped between adjacent housing sections. The actuating member 14 which is disposed concentrically of the valve stems 9a, 12a is formed as an assembly of components and comprises a main tubular element 18 flanged at its lower end, a cup-shaped member 19 screw-threaded into the upper end of element 18 and embodying a transverse wall 19a extending between the valve stems and provided with one or more perforations, and a guide sleeve 20 of anti-friction material embracing the element 18 and making sliding contact with the bore of enlargement 13a. The assembly also includes at its upper end a thrust plate 21 engaged by a spring 22 urging the actuating member to its lowermost position, the complete assembly being clamped together by the interengagement of element 18 and member 19. The actuator assembly is also attached to the diaphragms by the same clamping action, the diaphragms having beadings 15a, lea, respectively, on their inner edges which are received between the guide sleeve and the thrust plate 21 in the first instance and between the guide sleeve and the flanged end of element 18 in the second instance. The lower face of the element 18 where it normally bears up the lower wall of the housing is grooved or recessed such that the pressure existing in the discharge chamber 7 also acts upon the underside of diaphragm 16, and thus, as the two diaphragms are of equal area, the external pressures acting on the upper and lower sides of the diaphragm and actuator assembly are balanced. The space 23 beneath the upper diaphragm 15 is connected through a conduit 24 to the brake valve of an associated air pressure braking system, to the governor valve of the associated compressor unloader means or to an equivalent source of intermittent or fluctuating pressure and the drain valve operates as follows:

Normally the valve-actuating member 14 is urged by its loading spring 22 to a lowered position shown in which it holds the outlet valve 12 off its seating but is disengaged from the inlet valve stem 9a so that the inlet valve is seated. When the brakes are applied, or when the governor valve operates to effect unloading of the compressor, pressure is transmitted to the underside of the upper diaphragm 15 to lift the valve-actuating member 14. During the first part of this movement, the outlet valve 12 is allowed to close and thereafter the inlet valve 9 is lifted off its seating when any condensation which has collected in the drainage chamber 4 will be forced by reservoir pressure into the discharge chamber 7. The sequential operation of the outlet and inlet valves ensures that the reservoir cannot be vented to atmosphere, even momentarily. When pressure on the underside of the diaphragm 15 is released, the valve-actuating member 14 is restored to its initial position, first allowing the inlet valve to close and then opening the outlet valve so that liquid in the discharge chamber is ejected through the outlet port 10 by the residual reservoir pressure in said chamber.

I claim:

1. A condensate drain valve for a compressed air reservoir comprising a housing, means defining a discharge chamber within said housing, an inlet drain passage for connecting said reservoir to said chamber having an inlet port in said housing opening into said chamber, an inlet valve for said inlet port, means in said housing defining an outlet port from said discharge chamber, an outlet valve for said outlet port, valve actuating means reciprocable on a slide guide mounting within said housing and being adapted for operable connection to oppositely sequentially actuate said valves during movement in opposite directions, means for moving said valve actuating means comprising flexible diaphragm means connected to said valve actuating means and mounted within the housing, said diaphragm means extending within said housing to isolate said slide guide mounting of the valve I actuating means from said discharge chamber so that said slide guide mounting means is protected from condensate drainage from said reservoir and means for introducing fluid under operating pressure into said housing to cause said diaphragm means to displace said valve actuating means in a given direction to effect sequential closing of said outlet valve and opening of said inlet valve, said valve actuating means effecting sequential closing of said inlet valve and opening of said outlet valve when said fluid pressure is released.

2. The condensate drain valve defined in claim 1, wherein said drain passage comprises a drainage chamber at its inner end that is permanently open to the reservoir and is connected to said discharge chamber by said inlet port, said inlet valve blocking connection between said chambers when in closed position.

3. The condensate drain valve defined in claim 1, wherein said valve actuating means is a tubular member having said slide guide mounting in an internal housing bore, and said diaphragm means comprises axially spaced annular diaphragms peripherally secured to the housing and said actuating member and disposed to enclose said slide guide mounting therebetween.

4. The condensate drain valve defined in claim 3, wherein passage means is provided to apply the fluid pressure of the discharge chamber to the outwardly opposite sides of said diaphragms to provide pressure balance for said valve actuating means.

5. The condensate drain valve defined in claim 1, wherein said inlet and outlet ports and the valves therefor are coaxial in axially spaced relation, with both of said valves being spring biased toward closed position, and said valve actuator member is a tubular member slidable in an internal housing bore located axially between said ports and spring biased to engage and open said outlet valve and permit closure of said inlet valve when no operating fluid pressure is applied to said diaphragm means, said actuator member being displaced to allow said outlet valve to close and then engage and close said inlet valve when said operating pressure is applied to said diaphragm means.

6. In the condenate drain valve defined in claim 5, said diaphragm means comprising axially spaced annular diaphragms internally peripherally secured to opposite ends of said tubular actuator member at opposite ends of said slide guide bore and having their outer peripheries fixed to the housing, and said means for introducing operating fluid pressure being connected into the space on the opposite side of one of said diaphragms from said discharge chamber.

7. A condensate drain valve for a compressed air reservoir comprising a housing having a chamber therein, an inlet to said chamber adapted to be connected to the reservoir, an outlet from said chamber for opening to atmosphere, a valve seat in said inlet and in said outlet, biased closed valve means cooperating with said inlet valve seat seating in the direction of flow from the reservoir to the chamber, biased closed valve means cooperating with the outlet valve seat seating in the direction of flow from the chamber to atmosphere, hollow reciprocable means in said chamber between said valve means constructed and arranged to cooperate with said valve means to open the inlet valve means when reciprocated to a first osition, to open said outlet valve means when reciprocated to a second position and to permit both valve means to remain closed when being reciprocated through an intermediate position, a pair of spaced movable walls sealingly connecting said reciprocable means with the walls of the housing to define a closed annular chamber between said movable walls, annular wall means fixed within said housing and sealingly slidably receiving said reciprocable means to divide said closed annular chamber into a pair of sub chambers, one sub chamber being connected to a source of actuating fluid pressure and the other sub chamber being vented to atmosphere, and said spaced movable walls having equal and opposite effective areas open to the pressure of fluid between said valve means.

References Cited by the Examiner UNITED STATES PATENTS 2,286,282 6/1942 Joesting 137596.18 2,418,440 4/1947 White 137-20'4 2,910,088 10/1959 Natho 137625.5

ALAN COHAN, Primary Examiner. 

1. A CONDENSATE DRAIN VALVE FOR A COMPRESSED AIR RESERVOIR COMPRISING A HOUSING, MEANS DEFINING A DISCHARGE CHAMBER WITHIN SAID HOUSING, AN INLET DRAIN PASSAGE FOR CONNECTING SAID RESERVOIR TO SAID CHAMBER HAVING AN INLET PORT IN SAID HOUSING OPENING INTO SAID CHAMBER, AN INLET VALVE FOR SAID INLET PORT, MEANS IN SAID HOUSING DEFINING AN OUTLET PORT FROM SAID DISCHARGE CHAMBER, AN OUTLET VALVE FOR SAID OUTLET PORT, VALVE ACTUATING MEANS RECIPROCABLE ON A SLIDE GUIDE MOUNTING WITHIN SAID HOUSING AND BEING ADAPTED FOR OPERABLE CONNECTION TO OPPOSITELY SEQUENTIALLY ACTUATE SAID VALVES DURING MOVEMENT IN OPPOSITE DIRECTIONS, MEANS FOR MOVING SAID VALVE CONNECTED MEANS COMPRISING FLEXIBLE DIAPHRAGM MEANS CONNECTED TO SAID VALVE ACTUATING MEANS AND MOUNTED WITHIN THE HOUSING, SAID DIAPHRAGM MEANS EXTENDING WITHIN SAID 